Check out commander_keen's example here http://www.polycount.com/forum/showthread.php?t=74765 We have some more links here http://wiki.polycount.com/wiki/GrassTechnique
After reading the Ryse moss tutorial a while ago, I ended up doing some digging around the subject. After reading some papers I wondered if it could be used for other things such as grass. I managed to get a quick alright looking snow (image, image, gif) but grass proved much trickier. It seems that it might work if you…